1. Field of the Invention
The present invention relates to a pullback system, which has a simplified and miniaturized structure and an advanced function.
2. Background of the Invention
As ultrasonic technologies are gradually developed, ultrasonic mechanisms can be miniaturized to be inserted into a blood vessel of a human body and be used to analyze a state of a blood vessel such as an artery. This technique is called intravascular ultrasound (IVUS). To this end, using the speed of a sound, a time taken to transmit a vibration and to receive an ultrasound can be converted to a measurement of a distance or a depth.
Intravascular ultrasound is used for peripheral blood vessel as well as coronary arteries, and is referred to as intracoronary ultrasound, specifically, for the heart. Ultrasound having a diameter of about 1 mm may be used to observe the inside of a blood vessel. The state and type of an intracoronary lesion, and the degree and length of angiostenosis can be accurately analyzed using intravascular ultrasound. In plain language, intravascular ultrasound technologies are used to observe the inside of blood vessels.
Unlike two-dimensional shadow images according to coronary angiography, intravascular ultrasound uses a ultrasound that is directly introduced into a blood vessel, so that an observer can see the inside of the blood vessel, and thus, can understand and treat the blood vessel more accurately.
An ultrasonic catheter including a rotation transducer may be inserted into a blood vessel to perform an intravascular ultrasound process, thereby accurately analyzing an inner state of the blood vessel, such as a degree of hardening of a wall of the blood vessel and a degree of calcification thereof. Such a rotation transducer is inserted into an artery and is moved to a target region. In addition, the rotation transducer generates and receives ultrasonic pulses for forming and displaying an image of the surface shape and inner structure of the target region.
A 360-degree view of the inside of a blood vessel should be provided to perfectly depict target regions. To this end, the rotation transducer is rotated through 360 degrees. This is the reason why the term “rotation” is included in the name thereof.
In addition, the rotation transducer should be uniformly moved in the longitudinal direction thereof to scan long cell regions such as a blood vessel. To this end, a pullback system is needed as a pulling device.
To sum up, a pullback system for a catheter including a rotation transducer (hereinafter, referred to as just a pullback system) rotates the rotation transducer, and simultaneously, performs a pullback operation.
Referring to patent document 1, a conventional pullback system used for IVUS rotates a catheter including a rotation transducer by using a motor as a driving source, and simultaneously, performs a pullback operation for pulling the whole of the conventional pullback system at a constant speed. However, the conventional pullback system has the following limitations.
First, since the conventional pullback system uses a method of pulling the whole of a system for rotating the catheter including the rotation transducer, the entire structure of the conventional pullback system is enlarged and complicated, which may increase production costs and the weight and size of a device.
Secondly, when a structure that pulls back the whole of a device for rotating the catheter including the rotation transducer is provided, the catheter may be pulled back in a bending state. In this case, an error occurrence probability of a pulling distance is increased. An error in measuring a distance may decrease the accuracy of an intravascular diagnosis.